Yes, you do. a missing carb gasket will mess up your air/fuel mixture. Exhaust gasket, probably not much will happen, but I've heard that it's hard on the engines, probably because of the contrast of temperatures between exhaust gases and the environment.
When you say that the cylinder gasket is missing, do you mean the head gasket (between the cylinder and head), or the base gasket (between the crankcase and cylinder.)?
If it's the head gasket missing, you'll actually GAIN perfomance because it boosts compression when removed. If it's the base gasket, you'll LOSE performance because the intake and exhaust ports will be misaligned. You also might run a risk of the piston going too far up in the cylinder and past the end of it, causing piston, head, cylinder, and ring damage.
Check the resources section of this website to find a place to buy new gaskets if you need them.